WASHINGTON (Reuters) - They flirt, hold hands and guard
their lovers jealously -- yet they don't even have bones.

The love lives of octopuses are far more complex than
anyone thought, a team at the University of California,
Berkeley, reported on Monday.

Graduate student Christine Huffard snorkeled in the waters
off Indonesia to watch Abdopus aculeatus, an octopus with a
spiky tan body the size of a small orange and arms 8 to 10
inches long.

Octopuses are well studied in captivity but because they
are shy and often nocturnal, their natural wild behavior is
less understood.

ADVERTISEMENT

"Each day in the water, we learned something new about
octopus behavior, probably like what ornithologists must have
gone through after the invention of binoculars," said Huffard,
now at the Monterey Bay Aquarium Research Institute in Moss
Bay, California.

"We quickly realized that Abdopus aculeatus broke all the
rules, doing the near opposite of every hypothesis we'd formed
based on aquarium studies."

They saw male cephalopods guarding the dens of their mates
for several days, warding off rivals and even strangling them
if they got too close.

Small males would sneak in to mate by swimming low to the
ground in feminine fashion and not displaying their "male"
brown stripes, the researchers reported in the journal Marine
Biology.

And size matters, although perhaps not in quite the same
way as for humans.

"If you're going to spend time guarding a female, you want
to go for the biggest female you can find because she's going
to produce more eggs," biology professor Roy Caldwell said.
"It's basically an investment strategy."

Caldwell said he believes the behavior is common to many of
the nearly 300 species of octopus.

The animals usually mate several times a day once they
reach sexual maturity. Males have a specially designed arm they
use to deposit a sperm packet into the female, who retires to
her den and lays tens of thousands of eggs.

Both parents die within a few months of mating, leaving the
newborns to fend for themselves.